1. Field of the Invention
The present invention pertains to a method for obtaining improved seismic signal transmission through a well tubing wherein the tubing is deflected into engagement with a well casing or wellbore wall by a pressure force acting on a longitudinally displaceable end of the tubing.
2. Background
In many exploration and development operations in connection with the production of oil and gas from subterranean earth formations, it is necessary to transmit seismic and certain other types of signals between the earth formation and a sensor disposed in a well. For example, one exploration and development technique, commonly known as VSP, or vertical seismic profiling, is carried out by placing a seismic signal source or a seismic signal sensor at various depths in a well for transmitting or receiving signals through an earth formation surrounding the well. In other operations such as in hydraulically fracturing earth formations, it is desirable to monitor the growth and direction of extension of a fracture by placing seismic sensors in so-called monitor wells which are somewhat in proximity to the injection well.
One problem associated with signal transmission by way of a signal generating or receiving device disposed in a wellbore is the development of firm physical contact between the device and the wellbore wall. In certain operations, it may be desirable to place the signal generator or receiver device within an elongated tubing string extending within the well. However, it is difficult to place this tubing string in firm contact with the wellbore wall, including a casing or liner, so that a high quality signal path is provided between the device and the earth formation surrounding the well. The present method provides a unique solution to this problem which is applicable to certain signal transmission efforts when the signal generating or receiving device is to be placed within a tubing string extending within a well.